Spray a baking dish that fits inside the Instant Pot with a non-stick cooking spray (I used a 7-inch springform pan).
Make the pie crust
Put graham crackers, sugar and butter in a food processor and process until smooth. Press the crumb mixture into bottom and sides of your baking dish. Put the crust in the freezer while you are making the pie filling. (If you are looking for a gluten-free pie crust, you can use my walnut pie crust recipe)
Make the sweet potato pie filling
Put mashed sweet potatoes in a bowl, add butter and mix until combined. Add brown sugar, sweetened condensed milk, orange rind, vanilla, cinnamon, nutmeg and salt and mix until combined.
Pour the sweet potato filling into the crust.
Cook sweet potato pie in Instant Pot
Add 1 cup of water to the inner pot of the Instant Pot. Insert the trivet (the rack that comes with the Instant Pot) with the handles up. Carefully lower the pan with the sweet potato pie inside the Instant Pot on top of the trivet. DO NOT cover the baking pan with foil or any other cover.
Close the lid of the Instant Pot and turn the valve to a Sealing position. Press the "Pressure Cook" or "Manual" button and set the time to 35 minutes on High pressure.
When it's done cooking, let the pressure release naturally for 10 minutes, then quick release (QR) the steam. If the sweet potato pie is a little jiggly in the center, it is normal, it will firm up when it cools.
Carefully lift out the sweet potato pie from Instant Pot by the handles of the trivet (it will be very hot, so make sure to use heatproof gloves).
Let the sweet potato pie cool at room temperature. If serving the next day, refrigerate.